A networking architecture specified in the Data Over Cable Service Interface Specifications (DOCSIS) specifically includes a network management system, a service provisioning system, a cable modem termination system (CMTS), and multiple cable modems (CM) that access the CMTS by means of a hybrid fiber coaxial (HFC). Because many CMs access the CMTS, there is a one-to-many scenario. That is, multiple CMs share a bandwidth. In this case, time-division multiplexing is applied to upstream transmission, to ensure normal communication between the CMTS and each CM.
In the DOCSIS standard, a basic upstream service flow scheduling type is specifically defined, including: an unsolicited grant service (UGS), a real-time polling service (RTPS), a non-real-time polling service (NRTPS), best effort (BE), and the like. In the prior art, for a UGS service flow, a CMTS periodically and actively allocates a fixed bandwidth to a CM. The CM may periodically send data according to the allocated bandwidth, and does not need to send a request in advance. However, for the active bandwidth allocation manner, traffic to be sent by the CM cannot be learned in advance. Consequently, when the CM has no traffic or little traffic, there is bandwidth waste, and when the CM has burst traffic, the bandwidth is insufficient. For an RTPS service flow, a CMTS periodically allocates a unicast request opportunity, and this can meet a real-time transmission requirement of a service flow having variable traffic. This type needs more request overheads than UGS, but supports data having variable sizes, to obtain optimal transmission efficiency. For a BE flow, a contention-based bandwidth request opportunity is used, and a scheduling priority is lower than that of RTPS. Existing bandwidth allocation mainly depends on a request, and a CM needs to buffer data in a request phase, inevitably causing a delay. In addition, for some types of service flows, a piggyback solution may be used. Each time a CM uploads data, the CM may add a next bandwidth request to the data. However, bandwidth allocation in the piggyback solution mainly depends on a request, and the CM buffers data in a request phase, inevitably causing a delay.
To sum up, in a process in which a CMTS allocates bandwidth resources for various service flows of multiple CMs to ensure upstream communication of each CM that accesses the CMTS, because the allocation depends on a request, or a resource allocated to each CM is insufficient, a relatively large upstream transmission delay is caused.